<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <style>
    h1 {
      color: rgb(60, 144, 178);
      text-align: center;
    }

    .div{
      width: 0;
      height: 0;
      display: inline-block;
      border: 30px solid skyblue;
      border-color: transparent;
      border-bottom-color: royalblue;
    }
    .app{
      border: 1px solid gray;
      width: 300px;
      height: 1000px;
    }
    .wrap{
      margin-left: 50px;
    }
  </style>
  <title>Document</title>
</head>

<body>
  <div class="app">
    <h1>其他页面资源显示</h1>
    <div class="wrap">
      <span class="div"></span>
      <span class="div"></span>
      <span class="div"></span>
    </div>
    <div class="wrap">
      <span class="div"></span>
      <span class="div"></span>
      <span class="div"></span>
    </div>
    <div class="wrap">
      <span class="div"></span>
      <span class="div"></span>
      <span class="div"></span>
    </div>
  </div>
</body>

</html>